Composition and Interactions of the Oral–Gastrointestinal Microbiome Populations During Health, Disease, and Long-Duration Space Missions: A Narrative Review

The International Space Station (ISS) has around 3–5 crew members on-board at all times, and they normally stay on the ISS for about 5–7months in duration. Since March 2020, 170 long-duration space missions have occurred on the ISS. Thus, long-duration space missions are an integral part of space exploration and will only continue to expand in duration as missions to the Moon and Mars are on the horizon. However, long-duration space missions present several challenges to human crew members. Most of these challenges have been associated with physiological adaptation to microgravity, including motion sickness, muscle atrophy, and cardiovascular deconditioning. While not as well-studied, another major factor to consider when planning long-duration space missions is the psychological impact of the environment on the astronauts. Astronauts living in space will be unable to access natural landscapes and other environments found to have restorative effects on psychological stress and overall well-being. On top of being unable to access these restorative natural environments, astronauts will also be exposed to the stressful, unfamiliar environment of space. The purpose of this mini-review is to first summarize the literature related to stressors associated with space. Next, an overview of the large breadth of literature on the biophilia hypothesis and restorative environments will be provided, as these may serve as relatively simple and cost-effective solutions to mitigate the stress faced during long-duration space missions. Lastly, considerations related to the design of such environments in a space capsule as well as future directions will be presented.

The ability of human cells to adapt to space radiation is essential for the well-being of astronauts during long-distance space expeditions, such as voyages to Mars or other deep space destinations. However, the adaptation of the microbiomes should not be overlooked. Microorganisms inside an astronaut’s body, or inside the space station or other spacecraft, will also be exposed to radiation, which may induce resistance to antibiotics, UV, heat, desiccation, and other life-threatening factors. Therefore, it is essential to consider the potential effects of radiation not only on humans but also on their microbiomes to develop effective risk reduction strategies for space missions. Studying the human microbiome in space missions can have several potential benefits, including but not limited to a better understanding of the major effects space travel has on human health, developing new technologies for monitoring health and developing new radiation therapies and treatments. While radioadaptive response in astronauts’ cells can lead to resistance against high levels of space radiation, radioadaptive response in their microbiome can lead to resistance against UV, heat, desiccation, antibiotics, and radiation. As astronauts and their microbiomes compete to adapt to the space environment. The microorganisms may emerge as the winners, leading to life-threatening situations due to lethal infections. Therefore, understanding the magnitude of the adaptation of microorganisms before launching a space mission is crucial to be able to develop effective strategies to mitigate the risks associated with radiation exposure. Ensuring the safety and well-being of astronauts during long-duration space missions and minimizing the risks linked with radiation exposure can be achieved by adopting this approach.

The climate crisis, natural resource exploitation, and concerns around how to feed a growing world population have resulted in a growing chorus identifying the need for a Plan B. For some, this Plan B entails preparing for long-duration space missions and the development of human settlement on Mars. To plan for long-duration space missions, the development of food production technologies that can withstand extreme conditions such as poor soil, lack of gravity, and radiation are increasingly prioritized. These technologies may include genetic engineering, digital agriculture, 3D bioprinting, synthetically grown meat and more. Government and corporate proponents of long-duration space missions—NASA and SpaceX, among others—are actively funding agricultural research in space. They argue that the technologies developed for space will have positive implications beyond Mars—directly benefitting Earth and its inhabitants. This paper demonstrates that news reporting on the technology has been overall uncritical. Media narratives surrounding issues of food growth in space have not been studied. This study analyzes how English news media coverage (n= 170) from 67 publications report the feasibility of long-duration space missions, human settlements, and high-tech agricultural technologies. We provide a cross-section of the types of agricultural technologies being covered, the key organizations and actors in the field, and a critical analysis of media narratives. Using mixed methods content and discourse analysis, this study finds that the news media publications overwhelmingly portray long-duration space missions as both inevitable and a positive good for humanity. Without critically assessing the societal implications of food technologies for long-duration space missions vis-à-vis their benefits on Earth, we risk glossing over systemic and structural inequalities in the food system.

Advancements in health monitoring technologies for astronauts in deep space missions: A Review.

Martian Delight: Exploring qualitative contact for decoupled communications

In 2025, the Artemis II marks the first crewed mission orbiting the Moon, with plans for subsequent missions landing astronauts near the lunar South Pole and NASA aims to reach Mars by the 2030s. The growing interest in space underscores the increasing importance of long-term human presence in space missions. Challenges such as human health and sustainable food preservation persist in establishing settlements on other planetary bodies. Space agencies are developing regenerative life support systems utilizing hydroponic cultivation of plants and microalgae, fueled by crew waste as fertilizers. While biological systems could sustain astronauts, the predominantly vegan diets lack essential micronutrients. To address this, integrating microbial-based food supplements into current bioregenerative systems is crucial for ensuring a balanced diet and maintaining the health of space explorers. The aim of this project is to develop an alternative food system by growing microorganisms in space-related conditions and using their biomass, or products thereof, as food supplements for space travelers on long-duration space missions, e.g. to Mars. We select and study the impact of space conditions on microorganisms that can provide useful micronutrients for future space travelers, which cannot be fully provided by vegan diets. This will be done by selecting a range of candidate beneficial microorganisms. Various options are available, including Bacillus subtilis spp., which can produce riboflavin (vitamin B2) and whose spores have already been tested on Mars analog surfaces (Cortesão et al., 2019). Limosilactobacillus reuteri could be used as supplement of riboflavin (Spacova et al., 2022) and has previously been shown to increase its production of reuterin under simulated microgravity conditions (Senatore et al., 2020). In addition, the yeast Yarrowia lipolytica is a well-known producer of essential amino acids, PUFA, MUFA, and vitamin B complexes (Jach & Malm, 2022). Final strain selection will be based on (i) their ability and efficiency to produce micronutrients, (ii) their safety and health promoting (incl. Radiation protective) properties, (iii) their ability to survive and maintain production efficiency under extreme environments, including ionizing radiation and microgravity, and (iv) their compatibility with bio-based in situ resource utilization techniques (e.g., gas or mineral sources from Martian atmosphere or regolith through biomining) to increase loop-closure. The selected strains will be stored, revived and grown in simulated Martian conditions, to test their long-term stability and preservation as food supplement source. Through international collaborations, we will test these conditions using reduced-gravity simulators, space radiation analogs, and substrates based on lysed cells of bacteria previously grown on regolith simulants, such as Chroococcidopsis sp. (Billi et al., 2021), and Anabaena sp., which has already been used to grow Bacillus subtilis from its inactivated biomass (Verseux, 2018). At the end of this 4-year PhD research project, the expected outcome is to improve the nutritional well-being of future space travelers settling on other planets, and also to generate innovative insights applicable to Earth-based fields such as biotechnology, radioprotection, and environmental science. References Billi, D., Gallego Fernandez, B., Fagliarone, C., Chiavarini, S., & Rothschild, L. J. (2021). Exploiting a perchlorate-tolerant desert cyanobacterium to support bacterial growth for in situ resource utilization on Mars. International Journal of Astrobiology, 20(1), 29–35. https://doi.org/10.1017/S1473550420000300 Cortesão, M., Fuchs, F. M., Commichau, F. M., Eichenberger, P., Schuerger, A. C., Nicholson, W. L., Setlow, P., & Moeller, R. (2019). Bacillus subtilis spore resistance to simulated mars surface conditions. Frontiers in Microbiology, 10(FEB). https://doi.org/10.3389/fmicb.2019.00333 Jach, M. E., & Malm, A. (2022). Yarrowia lipolytica as an Alternative and Valuable Source of Nutritional and Bioactive Compounds for Humans. In Molecules (Vol. 27, Issue 7). MDPI. https://doi.org/10.3390/molecules27072300 Senatore, G., Mastroleo, F., Leys, N., & Mauriello, G. (2020). Growth of Lactobacillus reuteri DSM17938 under Two Simulated Microgravity Systems: Changes in Reuterin Production, Gastrointestinal Passage Resistance, and Stress Genes Expression Response. Astrobiology, 20(1), 1–14. https://doi.org/10.1089/ast.2019.2082 Spacova, I., Ahannach, S., Breynaert, A., Erreygers, I., Wittouck, S., Bron, P. A., Van Beeck, W., Eilers, T., Alloul, A., Blansaer, N., Vlaeminck, S. E., Hermans, N., & Lebeer, S. (2022). Spontaneous Riboflavin-Overproducing Limosilactobacillus reuteri for Biofortification of Fermented Foods. Frontiers in Nutrition, 9. https://doi.org/10.3389/fnut.2022.916607 Verseux, C. (2018). Resistance of cyanobacteria to space and Mars environments, in the frame of the EXPOSE-R2 space mission and beyond. https://doi.org/10.13140/RG.2.2.28437.88808

Innovative solutions are required to make long-duration space missions feasible. Crew performance and health is paramount to the success of anticipated Moon and Mars missions. Metabolic reduction via a quasi-torpor state is a possible mitigation strategy that can reduce consumable payload, which is necessary given the lack of available resupply options, and to reduce psychological stress, which is a risk for such lengthy missions. Even in lunar or cis-lunar missions, a quasi-torpor state could be implemented as an emergency countermeasure for critical situations where life support becomes limited. However, to date no studies have tested a quasi-torpor state in humans, and the impacts of intentional prolonged metabolic reduction on physiological and psychological parameters are unknown. To this end, we planned a three-phase study to provide proof-in-principle of the tolerability, feasibility, and side effects of a non-intravenous alpha-2-adrenergic receptor agonist for moderate sedation. This was accomplished by 1) determining the dosing and metabolic effects for different non-intravenous routes of alpha-2-adrenergic receptor agonist drugs; 2) assessing the degree of metabolic reduction and side effects during a 24-h quasi-torpor protocol; and 3) evaluating participant performance and total metabolic reduction achieved over a 5-day quasi-torpor protocol. We also aim to determine how skeletal muscle health and performance are affected by this quasi-torpor state. Quasi-torpor induced changes in skeletal muscle health and performance, as well as impacts on cognition and psychological stress, also have implications for terrestrial situations that result in prolonged confinement (e.g., austere environments such as submarine or remote scientific or military deployment and protracted critical illness). The findings of this three-phase study will be immediately applicable as a rescue strategy for emergencies during current or upcoming space missions. They will also identify key physiological and practical questions that need to be addressed for future deployment in long-duration space missions. This paper reviews the relevant literature that informed our rationale and approaches for this three-phase study.

Space agencies and private industries worldwide are planning long-duration missions, which come with complex medical challenges. Crews must be prepared for medical emergencies due to longer mission durations, increased travel distance, communication delays, and higher levels of isolation. This study aimed to systematically review the existing literature and knowledge gaps that could be related to the management of medical emergencies during long-duration space missions. A scoping review was conducted following the PRISMA extension for scoping reviews. Electronic databases, including ARC, Embase, IEEE Xplore, Medline Ovid, PsycINFO, and Web of Science, were searched from inception to June 1, 2023. Empirical study designs published in English or French were eligible for inclusion provided they described the management of at least 1 of 10 prioritized potentially mission-critical medical conditions. A total of 484 full-text studies were assessed for eligibility, with 99 included in this review. Conditions with the highest representation were spaceflight-associated neuro-ocular syndrome (N = 23), herniated disk (N = 22), and nephrolithiasis (N = 22). Conditions with the least representation were cerebrovascular accidents (N = 4), eye penetration (N = 3), and retinal detachment (N = 2). The duration of missions varied between 5 and 438 d for studies conducted in space. The data reflected the scarcity of evidence concerning prolonged deep-space exposure beyond the Earth's magnetosphere. Substantial medical autonomy is essential for the success of long-duration space missions, when medical support and even communication will be limited. Future research should prioritize knowledge gaps to improve preparedness and medical autonomy for space exploration activities. Tran K-A, Pollock NW, Dion P-M, Lapierre M, Tremblay S, Witteman W, Rhéaume C, Lafond D, Fortier F-A, Marion A, Dutil-Fafard L, Morin C, LePabic G, Monnot DPM, Archambault PM. Managing select medical emergencies during long-duration space missions. Aerosp Med Hum Perform. 2025; 96(2):143-154.

While expansion of space industry engineering standards over any human factors interface, except the humantechnology interface, is a still a relatively new topic (Dudley-Rowley & Bishop, 2002), even rarer still is the consideration of the latent challenges of long-duration space missions. A latent challenge in this venue could be a social, behavioral, or a natural or human-engineered environmental phenomenon. Manifest challenges to long-duration spaceflight are numerous enough, with mission planners, managers, and engineers taking into account obvious things like spacecraft operations, communications difficulties, having enough onboard resources, and protection of crew from an airless, microgravity environment fraught with radiation and other hazards. Latent challenges are harder to grasp. A latent challenge is any item, aspect, component, or process that potentially poses difficulties in the performance of mission objectives, but is something about which not much is known. However, a mission to Mars is a long-duration space mission that is a significantly different experience than a tour-of-duty of the same duration aboard a space station in full view of Earth, with easier access to new or needed equipment, more supplies, or even returnability. Social and behavioral phenomena in such an extreme environment could generate their own set of latent challenges. What steps could the crew take to ensure a high level of group functioning and minimize the impact to the accomplishment of mission objectives? How might design offset latent challenges on long-duration space missions? This report attempts to catalog the types of latent challenges that could pose difficulties to the longduration space mission, and then gives a multidisciplinary perspective of how design could respond to these challenges.

We estimate likelihood of presenting rhythms and survival to hospital discharge outcome after acute cardiac ischemia with arrhythmia and/or myocardial infarction (AMI) during long-duration space missions (LDSM) using selected terrestrial cohorts in medical literature. Medical scenarios were risk-stratified by coronary artery calcium score (CAC) and Framingham risk factors (FRF). AMI with and without sudden cardiac arrest (SCA) likelihoods and clinically significant rhythm scenarios and associated outcomes in "astronaut-like" cohorts were derived from two prospective trials identified by an evidence-based literature review. Results are presented using an event sequence diagram and event time line. The association of increasing CAC scores and FRF with AMI and SCA outcomes was calculated. Low AMI likelihoods are estimated in individuals with CAC scores of zero or < 100 and a low number of FRF. Survival rate to hospital discharge after out of hospital SCA in a large urban environment study was 5.2%. EMS-witnessed ventricular tachycardia and/or ventricular fibrillation survival rate of 37.5% represents < 1% of all urban out of hospital AMI, and these patients have a high proportion of known ischemic cardiovascular and pulmonary disease "disqualifying for spaceflight." Multiple factors may be expected to delay or defeat rapid access to "chain of survival" resources during LDSM, lowering survival rates below urban levels of 5.2%. Low CAC and FRF reflect lower risk for AMI events. Zero CAC was associated with the lowest risk of AMI after 3.5 yr of follow-up. Quantifiable incidence and outcome characterization suggests AMI in LDSM outcomes will be relatively independent of in-flight medical resources.

To describe postnatal changes in the populations of bacteria in the gastrointestinal tract (GIT) of dogs. 110 Beagles ranging from neonatal to adult dogs. Contents of the stomach and proximal and distal portions of the colon and contents and mucosa of the mid region of the small intestine were collected from puppies at 1 day after birth and subsequent suckling; puppies at 21, 42, and 63 days after birth; and adult female dogs (ie, dams of the puppies) for enumeration of bacterial populations. The entire GIT was colonized at day 1 by all groups of bacteria studied; aerotolerant forms were dominant. During subsequent postnatal development, there were changes in the relative proportions of the various groups of bacteria with anaerobic groups increasing in absolute and relative numbers. Establishment of bacterial populations in the GIT of dogs is a gradual process that begins immediately after birth. Age-related changes in the relative proportions of bacterial groups coincided with changes in diet and physiologic processes of the host and can influence nutritional state and disease resistance of developing dogs. Differences among regions of the GIT suggest that fecal samples may have limited use for understanding the populations of bacteria and the age and diet-related changes in various regions of the GIT.

25. Global Salivary Microbiome Activity In Female Adolescents With Anorexia Nervosa

This innovation introduces a next-generation autonomous space shuttle equipped with an advanced environmental regulation system, designed to maintain optimal living conditions in the extreme environment of space. At the core of this innovation lies an Arduino Uno microcontroller, which processes real-time data from a diverse array of sensors. These include the DHT11 for temperature and humidity, an LDR for light intensity, and newly integrated CO2, pressure, and radiation sensors. This expanded sensor network enables comprehensive monitoring of the shuttle’s internal environment, ensuring precise detection of critical parameters. An intelligent bot algorithm dynamically manages climate control by activating heating or cooling mechanisms as needed while also responding to CO2 concentrations, atmospheric pressure changes, and radiation levels. This autonomous system reduces the need for human intervention, fostering a self-sustaining habitat capable of adapting to internal fluctuations and external challenges. By enhancing sensor integration and employing adaptive control strategies, the shuttle ensures the safety of astronauts and the protection of sensitive equipment during long-duration space missions. This research represents a major advancement in space travel technology, offering a more resilient and responsive system for maintaining stable environmental conditions. The proposed solution not only improves the reliability of space missions but also marks a significant step toward future autonomous space exploration. Keywords: Autonomous Space Shuttle, Environmental Regulation System, Arduino Uno, Sensor Integration, Temperature and Humidity Monitoring, CO2 Detection, Pressure Sensing, Radiation Monitoring, Intelligent Bot Algorithm, Adaptive Climate Control, Self-Sustaining Habitat, Space Mission Reliability, Autonomous System, Long-Duration Spaceflight, Space Exploration, Real-Time Data Processing, Space Travel Safety, Dynamic Environmental Adjustment

What can we learn from the toughest animals of the Earth? Water bears (tardigrades) as multicellular model organisms in order to perform scientific preparations for lunar exploration

Recent advancements in stem cell biology, coupled with developments in space exploration, have opened new avenues for regenerative medicine. Microgravity environments in space induce significant physiological changes in the human body, such as muscle atrophy, decreased bone density, and immune system impairments, mimicking accelerated aging and chronic disease progression. These conditions offer a unique opportunity to study stem cell behavior, proliferation, and differentiation, which occur at a faster pace in space compared to Earth. The three-dimensional (3D) microgravity environment provides a more accurate representation of the human body’s natural state than traditional two-dimensional culture systems, fostering enhanced stem cell development. Among the various stem cells studied in space, mesenchymal stem cells (MSCs) have shown promise for therapeutic applications, including the treatment of stroke, cancer, and neurodegenerative diseases. Research aboard the International Space Station (ISS) has demonstrated that MSCs maintain their properties, proliferate, and differentiate under microgravity conditions, offering potential for future therapies. Additionally, MSCs exhibit resistance to space radiation, protecting astronauts from its harmful effects by promoting tissue repair and releasing regenerative factors. This radiation resistance, coupled with cryopreservation techniques, enables MSCs to be used in long-duration space missions. The ongoing research on MSCs in space not only supports astronaut health but also holds the potential to revolutionize regenerative medicine on Earth. By understanding how microgravity influences stem cell behavior, scientists are uncovering critical insights into tissue repair and cell function, paving the way for innovative treatments for aging-related diseases and other medical conditions. These findings highlight the broader implications of space-based stem cell research for advancing human health both in space and on Earth.